Along with development of wireless multimedia services, requirements of people on high data rate and user experiences increasingly grow, so that higher requirements on system capacity and coverage of a conventional cellular network are made. On the other hand, requirements of people on knowing about and communicating with interested persons or things nearby (i.e., Proximity-based Service (ProSe)) gradually increase along with prevailing of applications such as a social network, short-distance data sharing and local advertising. A conventional cell-based cellular network has obvious limitations in terms of support to high data rate and ProSe, and under such a requirement background, a D2D technology representative of a new direction of future development of communication technologies emerges. Application of a D2D technology may reduce a burden of a cellular network, reduce battery power consumption of UE, increase data rate, improve robustness of a network infrastructure and well meet the abovementioned requirements on a high-data rate service and ProSe.
A D2D technology may work in a licensed frequency band or an unlicensed frequency band, and allows direct discovery/direct communication of multiple pieces of UE supporting a D2D function (i.e., D2D UE) with a network infrastructure or without a network infrastructure. There are mainly three D2D application scenarios:
1) D2D UE1 and D2D UE2 perform data interaction under coverage of a cellular network, and user plane data does not pass through a network infrastructure, as shown in mode 1 in FIG 1;
2) UE in a weakly-covered/uncovered area performs relay transmission, as shown in mode 2 in FIG. 1, and D2D UE4 with relatively poor signal quality is allowed to communicate with the network through D2D UE3 covered by the network nearby, which may help an operating company to extend coverage and improve capacity; and
3) direct communication among equipment is allowed under the condition that the cellular network may not work normally in case of an earthquake or emergency, as shown in mode 3 in FIG. 1, and a control plane and user plane among D2D UE5, D2D UE6 and D2D UE7 may perform one-hop or multi-hop data communication without any network infrastructure.
A D2D technology usually includes a D2D discovery technology and a D2D communication technology: the D2D discovery technology refers to a technology arranged to judge/determine proximity between two or more pieces of D2D UE (for example, within a range where D2D direct communication may be performed) or arranged to judge/determine that first D2D UE is proximal to second D2D UE; and the D2D communication technology refers to a technology capable of implementing direct communication of part or all communication data between D2D UE without any network infrastructure.
D2D UE communication in a D2D communication group may adopt a one-to-many multicast communication manner, and in such a manner, all D2D UE in the group may receive data sent from a certain D2D UE in the group. While in the scenarios 2) and 3), D2D UE may serve as a relay node, then remote D2D UE on an edge of coverage of a cellular network or outside the coverage may perform cellular communication with the network through the relay D2D UE, and D2D communication may be performed between D2D UE through the relay D2D UE. In such a scenario, the remote D2D UE and the relay D2D UE communicate by adopting a one-to-one D2D communication manner. A Media Access Control Protocol Data Unit (MAC PDU) header of a D2D communication data packet includes source and target ID fields. For a D2D communication group, a content of the target ID field in the MAC PDU header is a D2D group ID (ProSe Layer-2 Group ID), and the D2D group ID is 24-bit, and is allocated by a Direct Provisioning Function (DPF) (a component of a ProSe function). While for one-to-one D2D communication, the content of the target ID field in the MAC PDU header is a terminal ID (ProSe terminal ID) of target D2D UE, and the terminal ID is also 24-bit, and may be preconfigured in Mobile Equipment (ME) or a Universal Integrated Circuit Card (UICC), or is arranged to the D2D UE by the ProSe function, or is allocated by the D2D UE itself, with its global uniqueness not ensured. During D2D communication, one-to-one unicast communication and one-to-many multicast communication may exist at the same time, there may exist the condition that a ProSe terminal ID of D2D UE for one-to-one unicast communication is the same as a ProSe terminal ID of another D2D UE for one-to-one unicast communication or the ProSe terminal ID of the D2D UE for one-to-one unicast communication is the same as a D2D group ID (ProSe Layer-2 Group ID) for one-to-many multicast communication, and then the D2D UE and all D2D UE in a D2D communication group with the same ID may all receive a unicast or multicast MAC PDU data packet with the same ID. For example, D2D UE 2 and D2D UE 3 in FIG. 2 belong to the same D2D communication group and may perform D2D group communication, D2D UE 1 does not belong to the D2D communication group, but the D2D UE 1 may perform one-to-one D2D discovery/communication with the D2D UE 2 or the D2D UE 3. There is made such a hypothesis that a unicast ProSe terminal ID of the D2D UE 1 is the same as a ProSe Layer-2 Group ID of a ProSe communication group, and then the D2D UE 1 and D2D UE (including the D2D UE 2 and the D2D UE 3) of the D2D communication group may all receive a MAC PDU with the same ID. There is yet no method capable of solving such a D2D ID conflict problem in a related technology.